Draft White Paper 

SC&A’S SUMMARY EVALUATION OF DWE ERRORS 

(BLUNDERS) IN WELDON SPRING DATA 

Contract Number 200-2009-28555 

Prepared by 

Ron Buchanan, PhD, CHP 

S. Cohen & Associates 

1608 Spring Hill Road, Suite 400 

Vienna, Virginia 22182 

Saliant, Inc. 

5579 Catholic Church Road 

Jefferson, Maryland 21755 

February 2012 

Disclaimer 

This document is made available in accordance with the unanimous desire of the Advisory Board on 

Radiation and Worker Health (ABRWH) to maintain all possible openness in its deliberations. However, 

the ABRWH and its contractor, SC&A, caution the reader that at the time of its release, this report is predecisional and has not been reviewed by the Board for factual accuracy or applicability within the 

requirements of 42 CFR 82. This implies that once reviewed by the ABRWH, the Board’s position may 

differ from the report’s conclusions. Thus, the reader should be cautioned that this report is for 

information only and that premature interpretations regarding its conclusions are unwarranted.
Effective Date: 

February 23, 2012 

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NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82.

Document No. 

SC&A’s Summary Evaluation of DWE Errors

Effective Date: 

 Draft – February 23, 2012 

S. COHEN & ASSOCIATES: 

Technical Support for the Advisory Board on 

Radiation & Worker Health Review of 

NIOSH Dose Reconstruction Program Revision No. 

0 (Draft) 

SC&A’s Summary Evaluation of DWE Errors 

(Blunders) In Weldon Spring Data Page 2 of 5 

Task Manager: 

________________________ Date:____________ 

Ron Buchanan, PhD, CHP 

Supersedes: 

N/A 

Project Manager: 

________________________ Date:____________ 

John Stiver, CHP 

Peer Reviewer(s): 

 John Stiver 

Record of Revisions 

Revision 

Number 

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Date Description of Revision 

0 (Draft) 02/23/2012 Initial issue 
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NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82.

 

1.0 INTRODUCTION 

On September 7, 2011, the National Institute for Occupational Safety and Health (NIOSH) 

provided a response (NIOSH 2011a, Rev. 00) to the Weldon Spring Site (WSS) Special 

Exposure Cohort (SEC) issue (SC&A 2010) concerning errors, or sometimes called “blunders,”1

in the original daily weighted exposure (DWE), or sometimes referred to as daily weighted 

average (DWA), air concentration data as discussed at the WSS Work Group meeting on May 9, 

2011. On September 27, 2011, SC&A issued an evaluation of that paper (SC&A 2011). 

On November 28, 2011, NIOSH issued Rev. 01 to their original September 7, 2011, paper 

(NIOSH 2011b). 

On January 17, 2012, SC&A issued their evaluation (SC&A 2012) of NIOSH’s November 28, 

2011, Rev. 01, response. 

A Weldon Spring Work Group conference call meeting was held on February 14, 2012, in which 

the issue of errors in WSS DWA data was discussed. The following is a summary of that 

discussion and the conclusions reached. 

2.0 SUMMARY OF FEBRUARY 14, 2012 CONFERENCE CALL CONCERNING 

WSS ISSUE #1b, ERRORS IN DWE DATA 

In SC&A’s evaluation (SC&A 2012) of NIOSH’s response to the issue of errors in the DWE 

original data (NIOSH 2011a and NIOSH 2011b), the following areas of concern were addressed: 

 Limited data 

 Representativeness of the limited data 

 Type and magnitude of errors 

 Application of findings

In the evaluation report (SC&A 2012), SC&A found that for Item #3, the type and magnitude of 

errors identified in the WSS DWE data were similar to those found in other studies concerned 

with errors associated with data transcription and manual calculations based on field-recorded 

data. Additionally, SC&A found that for Item #4, NIOSH’s method of deriving and applying the 

results of the DWE errors for dose reconstruction purposes is appropriate. However, SC&A 

continues to have concerns with how the data were selected for the error analyses (Item #1), and 

how well the uranium DWE error data represented thorium DWE errors (Item #2). 

Item #1 – Limited data 

SC&A had concerns that while some of the available original data in the SRDB documents 

referenced by NIOSH in their DWE error analyses was used, other pages of the original data 

were not used. SC&A inquired as to the bases for the selection of the data that were used in the 

1 The ISO definition emphasizes that a blunder is often considered a serious mistake caused by ignorance 

or confusion; stupidity, which is included in some U.S. English definitions of blunder, is not implied in this case 

(ISO 1995). 
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NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82.

NIOSH DWE error analyses. It was found that NIOSH used only those original data sheets that 

had corresponding calculation summary sheets. This allowed a direct comparison of entries in 

the original data sheets to those transcribed to the summary sheets and an analysis of their use in 

the calculation of DWE. Original data sheets and calculational summary sheets were not used 

unless there was a direct documented link between them. While this approach resulted in less 

data to analyze, it nonetheless ensured a one-to-one correspondence between the original data 

and the calculational summary sheet for each set of data used in the error analyses. 

Item 2 – Representativeness of the limited data 

NIOSH did not find any of the original data sheets, only summary calculational data sheets, for 

the thorium DWE values to be used in dose reconstruction. Instead, the error analyses were 

performed using uranium DWE data. SC&A recognizes that for any given operator, the human 

errors associated with data recording and calculations would be similar for both thorium and 

uranium. Thus, the use of uranium data to assess the error rate for thorium data is appropriate if 

the same operators processed the data or if the error types and rates were similar for different 

operators. SC&A was concerned that the errors in the uranium DWE data might not be 

representative of the errors in the thorium DWE data, since only 17 of the 82 lines of data in 

NIOSH’s error analyses reports (NIOSH 2011a and NIOSH 2011b) represented the thorium 

processing era of 1963–1966 at the WSS. However, in evaluating the data available for error 

analyses, SC&A did not find that additional analyses and/or investigations would result in 

significant changes in the error rate and dose reconstruction correction factors, as already derived 

from the uranium DWE data. 

3.0 SUMMARY 

SC&A found the NIOSH error analyses methods and the recommendations for application to 

dose reconstruction to be acceptable for thorium DWE data at the WSS. SC&A finds that there 

were limited DWE data available for the era that thorium was used at the WSS. Despite the 

limited data, however, the types and magnitudes of errors in the WSS data are consistent with 

those observed in Davis and Strom (2008) and a recent NIOSH error analysis for Fernald, a sister 

plant to WSS that employed the same processes and DWE methodologies (NIOSH 2012). 

SC&A also notes that the Fernald analysis, which did not suffer from data limitations, 

demonstrated an error rate of about 1%, much lower than for WSS. Thus, while it would have 

been advantageous to have had more data representative of thorium processing at WSS, we 

believe that additional resources and investigations are not likely to impact the resulting error 

correction factors significantly. 

4.0 REFERENCES 

Davis, A.J., and D.J. Strom, 2008. Uncertainty and Variability in Historical Time-Weighted Average 

Exposure Data, Health Physics, Vol. 94. February 2008. SRDB 41616.

NIOSH 2011a. White Paper for Weldon Spring Plant – Evaluation of Blunders Associated with 

Daily Weighted Average (DWA) Reports at the Weldon Spring Plant, Rev. 00. National Institute 

for Occupational Safety and Health, Office of Compensation Analysis and Support, Cincinnati, 

Ohio. September 7, 2011. 
Effective Date: 

February 23, 2012 

Revision No. 

0 (Draft) 

Document No. 

SC&A’s Summary Evaluation of DWE Errors 

Page No. 

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 This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82.

NOTICE:

NIOSH 2011b. White Paper for Weldon Spring Plant - Evaluation of Blunders Associated with 

Daily Weighted Average (DWA) Reports at the Weldon Spring Plant, Rev. 01. National Institute 

for Occupational Safety and Health, Office of Compensation Analysis and Support, Cincinnati, 

Ohio. November 28, 2011.

NIOSH 2012. White Paper: Evaluation of Blunders Associated with Daily Weighted Exposure 

(DWE) Reports at Fernald (FMPC), Rev. 00. National Institute for Occupational Safety and 

Health, Office of Compensation Analysis and Support, Cincinnati, Ohio. February 7, 2012.

ISO 1995. “Guide to the expression of uncertainty in measurement.” International Organization 

for Standardization, Geneva. 1995. 

SC&A 2010. Preliminary Issues from SC&A’s Review of NIOSH’s Evaluation Report for the 

Weldon Spring Site, Weldon Spring, Missouri, Special Exposure Cohort Petition SEC-00143. 

SCA-TR-TASK5-0015. SC&A, Inc., Vienna, Virginia, and Saliant, Inc., Jefferson, Maryland. 

October 2010. 

SC&A 2011. SC&A’s Evaluation of NIOSH’s Response of September 7, 2011, to Daily 

Weighted Exposure Blunders in Weldon Spring Data. SCA-TR-TASK5-0015. SC&A, Inc., 

Vienna, Virginia, and Saliant, Inc., Jefferson, Maryland. September 2011. 

SC&A 2012. Evaluation of NIOSH’s Response to SC&A’s Concerns Regarding DWE Errors 

(Blunders) in Weldon Spring Data. SCA-TR-TASK5-0015. SC&A, Inc., Vienna, Virginia, and 

Saliant, Inc., Jefferson, Maryland. January 17, 2012.